On geometric partition mode with intra and inter prediction

ABSTRACT

Coded information of a coding unit (CU) is received. The CU is partitioned into a first partition and a second partition based on a partition index. The partition index indicates a geometric partition mode (GPM) in which the CU is partitioned into the first partition and the second partition by a straight partition line. Based on a location of the straight partition line in the CU, (i) whether a first prediction mode of the first partition of the CU is one of an intra mode and an inter mode and (ii) whether a second prediction mode of the second partition of the CU is one of the intra mode and the inter mode are determined. The first partition of the CU is reconstructed based on the determined first prediction mode and the second partition of the CU is reconstructed based on the determined second prediction mode.

INCORPORATION BY REFERENCE

This present disclosure claims the benefit of priority to U.S.Provisional Application No. 63/252,111, “Geometric Partition Mode withIntra and Inter Prediction” filed on Oct. 4, 2021, which is incorporatedby reference herein in its entirety.

TECHNICAL FIELD

The present disclosure describes embodiments generally related to videocoding.

BACKGROUND

The background description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent the work is described in thisbackground section, as well as aspects of the description that may nototherwise qualify as prior art at the time of filing, are neitherexpressly nor impliedly admitted as prior art against the presentdisclosure.

Uncompressed digital video can include a series of pictures, eachpicture having a spatial dimension of, for example, 1920×1080 luminancesamples and associated chrominance samples. The series of pictures canhave a fixed or variable picture rate (informally also known as framerate), of, for example 60 pictures per second or 60 Hz. Uncompressedvideo has specific bitrate requirements. For example, 1080p60 4:2:0video at 8 bit per sample (1920×1080 luminance sample resolution at 60Hz frame rate) requires close to 1.5 Gbit/s bandwidth. An hour of suchvideo requires more than 600 GBytes of storage space.

One purpose of video coding and decoding can be the reduction ofredundancy in the input video signal, through compression. Compressioncan help reduce the aforementioned bandwidth and/or storage spacerequirements, in some cases by two orders of magnitude or more. Bothlossless compression and lossy compression, as well as a combinationthereof can be employed. Lossless compression refers to techniques wherean exact copy of the original signal can be reconstructed from thecompressed original signal. When using lossy compression, thereconstructed signal may not be identical to the original signal, butthe distortion between original and reconstructed signals is smallenough to make the reconstructed signal useful for the intendedapplication. In the case of video, lossy compression is widely employed.The amount of distortion tolerated depends on the application; forexample, users of certain consumer streaming applications may toleratehigher distortion than users of television distribution applications.The compression ratio achievable can reflect that: higherallowable/tolerable distortion can yield higher compression ratios.

A video encoder and decoder can utilize techniques from several broadcategories, including, for example, motion compensation, transform,quantization, and entropy coding.

Video codec technologies can include techniques known as intra coding.In intra coding, sample values are represented without reference tosamples or other data from previously reconstructed reference pictures.In some video codecs, the picture is spatially subdivided into blocks ofsamples. When all blocks of samples are coded in intra mode, thatpicture can be an intra picture. Intra pictures and their derivationssuch as independent decoder refresh pictures, can be used to reset thedecoder state and can, therefore, be used as the first picture in acoded video bitstream and a video session, or as a still image. Thesamples of an intra block can be exposed to a transform, and thetransform coefficients can be quantized before entropy coding. Intraprediction can be a technique that minimizes sample values in thepre-transform domain. In some cases, the smaller the DC value after atransform is, and the smaller the AC coefficients are, the fewer thebits that are required at a given quantization step size to representthe block after entropy coding.

Traditional intra coding such as known from, for example MPEG-2generation coding technologies, does not use intra prediction. However,some newer video compression technologies include techniques thatattempt, from, for example, surrounding sample data and/or metadataobtained during the encoding and/or decoding of spatially neighboring,and preceding in decoding order, blocks of data. Such techniques arehenceforth called “intra prediction” techniques. Note that in at leastsome cases, intra prediction is using reference data only from thecurrent picture under reconstruction and not from reference pictures.

There can be many different forms of intra prediction. When more thanone of such techniques can be used in a given video coding technology,the technique in use can be coded in an intra prediction mode. Incertain cases, modes can have submodes and/or parameters, and those canbe coded individually or included in the mode codeword. Which codewordto use for a given mode, submode, and/or parameter combination can havean impact in the coding efficiency gain through intra prediction, and socan the entropy coding technology used to translate the codewords into abitstream.

A certain mode of intra prediction was introduced with H.264, refined inH.265, and further refined in newer coding technologies such as jointexploration model (JEM), versatile video coding (VVC), and benchmark set(BMS). A predictor block can be formed using neighboring sample valuesbelonging to already available samples. Sample values of neighboringsamples are copied into the predictor block according to a direction. Areference to the direction in use can be coded in the bitstream or mayitself be predicted.

Referring to FIG. 1A, depicted in the lower right is a subset of ninepredictor directions known from H.265's 33 possible predictor directions(corresponding to the 33 angular modes of the 35 intra modes). The pointwhere the arrows converge (101) represents the sample being predicted.The arrows represent the direction from which the sample is beingpredicted. For example, arrow (102) indicates that sample (101) ispredicted from a sample or samples to the upper right, at a 45 degreeangle from the horizontal. Similarly, arrow (103) indicates that sample(101) is predicted from a sample or samples to the lower left of sample(101), in a 22.5 degree angle from the horizontal.

Still referring to FIG. 1A, on the top left there is depicted a squareblock (104) of 4×4 samples (indicated by a dashed, boldface line). Thesquare block (104) includes 16 samples, each labelled with an “S”, itsposition in the Y dimension (e.g., row index) and its position in the Xdimension (e.g., column index). For example, sample S21 is the secondsample in the Y dimension (from the top) and the first (from the left)sample in the X dimension. Similarly, sample S44 is the fourth sample inblock (104) in both the Y and X dimensions. As the block is 4×4 samplesin size, S44 is at the bottom right. Further shown are reference samplesthat follow a similar numbering scheme. A reference sample is labelledwith an R, its Y position (e.g., row index) and X position (columnindex) relative to block (104). In both H.264 and H.265, predictionsamples neighbor the block under reconstruction; therefore no negativevalues need to be used.

Intra picture prediction can work by copying reference sample valuesfrom the neighboring samples as appropriated by the signaled predictiondirection. For example, assume the coded video bitstream includessignaling that, for this block, indicates a prediction directionconsistent with arrow (102)—that is, samples are predicted from aprediction sample or samples to the upper right, at a 45 degree anglefrom the horizontal. In that case, samples S41, S32, S23, and S14 arepredicted from the same reference sample R05. Sample S44 is thenpredicted from reference sample R08.

In certain cases, the values of multiple reference samples may becombined, for example through interpolation, in order to calculate areference sample; especially when the directions are not evenlydivisible by 45 degrees.

The number of possible directions has increased as video codingtechnology has developed. In H.264 (year 2003), nine different directioncould be represented. That increased to 33 in H.265 (year 2013), andJEM/VVC/BMS, at the time of disclosure, can support up to 65 directions.Experiments have been conducted to identify the most likely directions,and certain techniques in the entropy coding are used to represent thoselikely directions in a small number of bits, accepting a certain penaltyfor less likely directions. Further, the directions themselves cansometimes be predicted from neighboring directions used in neighboring,already decoded, blocks.

FIG. 1B shows a schematic (110) that depicts 65 intra predictiondirections according to JEM to illustrate the increasing number ofprediction directions over time.

The mapping of intra prediction directions bits in the coded videobitstream that represent the direction can be different from videocoding technology to video coding technology; and can range, forexample, from simple direct mappings of prediction direction to intraprediction mode, to codewords, to complex adaptive schemes involvingmost probable modes, and similar techniques. In all cases, however,there can be certain directions that are statistically less likely tooccur in video content than certain other directions. As the goal ofvideo compression is the reduction of redundancy, those less likelydirections will, in a well working video coding technology, berepresented by a larger number of bits than more likely directions.

Video coding and decoding can be performed using inter-pictureprediction with motion compensation. Motion compensation can be a lossycompression technique and can relate to techniques where a block ofsample data from a previously reconstructed picture or part thereof(reference picture), after being spatially shifted in a directionindicated by a motion vector (MV henceforth), is used for the predictionof a newly reconstructed picture or picture partition. In some cases,the reference picture can be the same as the picture currently underreconstruction. MVs can have two dimensions X and Y, or threedimensions, the third being an indication of the reference picture inuse (the latter, indirectly, can be a time dimension).

In some video compression techniques, an MV applicable to a certain areaof sample data can be predicted from other MVs, for example from thoserelated to another area of sample data spatially adjacent to the areaunder reconstruction, and preceding that MV in decoding order. Doing socan substantially reduce the amount of data required for coding the MV,thereby removing redundancy and increasing compression. MV predictioncan work effectively, for example, because when coding an input videosignal derived from a camera (known as natural video) there is astatistical likelihood that areas larger than the area to which a singleMV is applicable move in a similar direction and, therefore, can in somecases be predicted using a similar motion vector derived from MVs ofneighboring area. That results in the MV found for a given area to besimilar or the same as the MV predicted from the surrounding MVs, andthat in turn can be represented, after entropy coding, in a smallernumber of bits than what would be used if coding the MV directly. Insome cases, MV prediction can be an example of lossless compression of asignal (namely: the MVs) derived from the original signal (namely: thesample stream). In other cases, MV prediction itself can be lossy, forexample because of rounding errors when calculating a predictor fromseveral surrounding MVs.

Various MV prediction mechanisms are described in H.265/HEVC (ITU-T Rec.H.265, “High Efficiency Video Coding”, December 2016). Out of the manyMV prediction mechanisms that H.265 offers, described here is atechnique henceforth referred to as “spatial merge”.

Referring to FIG. 2 , a current block (201) comprises samples that havebeen found by the encoder during the motion search process to bepredictable from a previous block of the same size that has beenspatially shifted. Instead of coding that MV directly, the MV can bederived from metadata associated with one or more reference pictures,for example from the most recent (in decoding order) reference picture,using the MV associated with either one of five surrounding samples,denoted A0, A1, and B0, B1, B2 (202 through 206, respectively). InH.265, the MV prediction can use predictors from the same referencepicture that the neighboring block is using.

SUMMARY

Aspects of the disclosure provide methods and apparatuses for videoencoding/decoding. In some examples, an apparatus for video decodingincludes processing circuitry.

According to an aspect of the disclosure, a method of video decodingperformed in a video decoder is provided. In the method, codedinformation of a coding unit (CU) in a current picture can be receivedfrom a coded video bitstream. The CU can be partitioned into a firstpartition and a second partition based on a partition index in the codedinformation. The partition index can indicate a geometric partition mode(GPM) in which the CU is partitioned into the first partition and thesecond partition by a straight partition line. Based on a location ofthe straight partition line in the CU, (i) whether a first predictionmode of the first partition of the CU is one of an intra mode and aninter mode and (ii) whether a second prediction mode of the secondpartition of the CU is one of the intra mode and the inter mode can bedetermined. The first partition of the CU can be reconstructed based onthe determined first prediction mode and the second partition of the CUcan be reconstructed based on determined the second prediction mode.

In an example, in response to the straight partition line intersecting atop left corner of the CU, the first prediction mode of the firstpartition can be determined as the intra mode and the second predictionmode of the second partition can be determined as the inter mode basedon a width of the CU being equal to or larger than a height of the CU.

In another example, in response to the straight partition lineintersecting a top left corner of the CU, the first prediction mode ofthe first partition can be determined as the inter mode and the secondprediction mode of the second partition can be determined as the intramode based on a width of the CU being smaller than a height of the CU.

In yet another example, in response to the straight partition lineintersecting a top left corner of the CU, the first prediction mode ofthe first partition and the second prediction mode of the secondpartition can be determined based on which of a top reference sample anda left reference sample adjacent to the CU is available for intraprediction.

For example, based on (i) the left reference sample being adjacent tothe first partition of the CU and available for the intra prediction and(ii) the top reference sample being unavailable for the intraprediction, the first prediction mode of the first partition can bedetermined as the intra mode and the second prediction mode of thesecond partition can be determined as the inter mode.

In some embodiments, the first prediction mode of the first partitionand the second prediction mode of the second partition can be determinedbased on which one of the first partition and the second partition ofthe CU contains a larger portion of a top corner pixel of the CU.

In some embodiments, based on the first partition of the CU containingthe larger portion of the top corner pixel of the CU, the firstprediction mode of the first partition can be determined as the intramode and the second prediction mode of the second partition can bedetermined as the inter mode.

In some embodiments, in response to a first portion of the top cornerpixel contained in the first partition being equal to a second portionof the top corner pixel contained in the second partition, the firstprediction mode and the second prediction mode can be determined basedon which of a top reference sample and a left reference sample areadjacent to one of the first partition and the second partition.

In some embodiments, whether the first partition of the CU is intracoded or inter coded can be determined based on a first index. Whetherthe second partition of the CU is intra coded or inter coded can bedetermined based on a second index. In response to one of the firstpartition and the second partition being intra coded and another one ofthe first partition and the second partition being inter coded, theintra mode can be determined from an intra mode list for the one of thefirst partition and the second partition that is intra coded based on anintra mode index that is included in the coded information. A mergecandidate for the inter mode can be determined from a merge candidatelist for the other one of the first partition and the second partitionthat is inter coded based on a merge index that is included in the codedinformation.

In the method, whether one of the first partition and the secondpartition of the CU is intra coded and another one of the firstpartition and the second partition of the CU is inter coded can bedetermined based on a flag included in the coded information. Inresponse to the one of the first partition and the second partition ofthe CU being intra coded and the other one of the first partition andthe second partition of the CU being inter coded, the intra mode can bedetermined from an intra mode list for the one of the first partitionand the second partition that is intra coded based on an intra modeindex included in the coded information. A merge candidate for the intermode can be determined from a merge candidate list for the other one ofthe first partition and the second partition that is inter coded basedon a merge index included in the coded information.

According to another aspect of the disclosure, an apparatus is provided.The apparatus includes processing circuitry. The processing circuitrycan be configured to perform any of the methods for video coding.

Aspects of the disclosure also provide a non-transitorycomputer-readable medium storing instructions which when executed by acomputer for video decoding cause the computer to perform the method forvideo decoding.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features, the nature, and various advantages of the disclosedsubject matter will be more apparent from the following detaileddescription and the accompanying drawings in which:

FIG. 1A is a schematic illustration of an exemplary subset of intraprediction modes.

FIG. 1B is an illustration of exemplary intra prediction directions.

FIG. 2 is a schematic illustration of a current block and itssurrounding spatial merge candidates in one example.

FIG. 3 is a schematic illustration of a simplified block diagram of acommunication system (300) in accordance with an embodiment.

FIG. 4 is a schematic illustration of a simplified block diagram of acommunication system (400) in accordance with an embodiment.

FIG. 5 is a schematic illustration of a simplified block diagram of adecoder in accordance with an embodiment.

FIG. 6 is a schematic illustration of a simplified block diagram of anencoder in accordance with an embodiment.

FIG. 7 shows a block diagram of an encoder in accordance with anotherembodiment.

FIG. 8 shows a block diagram of a decoder in accordance with anotherembodiment.

FIG. 9 shows exemplary positions of spatial merge candidates withanother embodiment.

FIG. 10 shows an exemplary redundancy check of spatial merge candidates.

FIG. 11 shows a schematic illustration of motion vector scaling for atemporal merge candidate in accordance with an embodiment.

FIG. 12 shows exemplary candidate positions for temporal mergecandidates in accordance with an embodiment.

FIG. 13 shows exemplary angle distributions of a geometric partitionmode (GPM) in accordance with an embodiment.

FIG. 14 shows exemplary partition lines for the GPM in accordance withan embodiment.

FIG. 15A shows a first exemplary partition of the GPM in accordance withan embodiment.

FIG. 15B shows a second exemplary partition of the GPM in accordancewith an embodiment.

FIG. 15C shows a third exemplary partition of the GPM in accordance withan embodiment.

FIG. 16 shows a flow chart outlining an exemplary decoding processaccording to some embodiments of the disclosure.

FIG. 17 shows a flow chart outlining an exemplary encoding processaccording to some embodiments of the disclosure.

FIG. 18 is a schematic illustration of a computer system in accordancewith an embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 3 illustrates a simplified block diagram of a communication system(300) according to an embodiment of the present disclosure. Thecommunication system (300) includes a plurality of terminal devices thatcan communicate with each other, via, for example, a network (350). Forexample, the communication system (300) includes a first pair ofterminal devices (310) and (320) interconnected via the network (350).In the FIG. 3 example, the first pair of terminal devices (310) and(320) performs unidirectional transmission of data. For example, theterminal device (310) may code video data (e.g., a stream of videopictures that are captured by the terminal device (310)) fortransmission to the other terminal device (320) via the network (350).The encoded video data can be transmitted in the form of one or morecoded video bitstreams. The terminal device (320) may receive the codedvideo data from the network (350), decode the coded video data torecover the video pictures and display video pictures according to therecovered video data. Unidirectional data transmission may be common inmedia serving applications and the like.

In another example, the communication system (300) includes a secondpair of terminal devices (330) and (340) that performs bidirectionaltransmission of coded video data that may occur, for example, duringvideoconferencing. For bidirectional transmission of data, in anexample, each terminal device of the terminal devices (330) and (340)may code video data (e.g., a stream of video pictures that are capturedby the terminal device) for transmission to the other terminal device ofthe terminal devices (330) and (340) via the network (350). Eachterminal device of the terminal devices (330) and (340) also may receivethe coded video data transmitted by the other terminal device of theterminal devices (330) and (340), and may decode the coded video data torecover the video pictures and may display video pictures at anaccessible display device according to the recovered video data.

In the FIG. 3 example, the terminal devices (310), (320), (330) and(340) may be illustrated as servers, personal computers and smart phonesbut the principles of the present disclosure may be not so limited.Embodiments of the present disclosure find application with laptopcomputers, tablet computers, media players and/or dedicated videoconferencing equipment. The network (350) represents any number ofnetworks that convey coded video data among the terminal devices (310),(320), (330) and (340), including for example wireline (wired) and/orwireless communication networks. The communication network (350) mayexchange data in circuit-switched and/or packet-switched channels.Representative networks include telecommunications networks, local areanetworks, wide area networks and/or the Internet. For the purposes ofthe present discussion, the architecture and topology of the network(350) may be immaterial to the operation of the present disclosureunless explained herein below.

FIG. 4 illustrates, as an example for an application for the disclosedsubject matter, the placement of a video encoder and a video decoder ina streaming environment. The disclosed subject matter can be equallyapplicable to other video enabled applications, including, for example,video conferencing, digital TV, storing of compressed video on digitalmedia including CD, DVD, memory stick and the like, and so on.

A streaming system may include a capture subsystem (413), that caninclude a video source (401), for example a digital camera, creating forexample a stream of video pictures (402) that are uncompressed. In anexample, the stream of video pictures (402) includes samples that aretaken by the digital camera. The stream of video pictures (402),depicted as a bold line to emphasize a high data volume when compared toencoded video data (404) (or coded video bitstreams), can be processedby an electronic device (420) that includes a video encoder (403)coupled to the video source (401). The video encoder (403) can includehardware, software, or a combination thereof to enable or implementaspects of the disclosed subject matter as described in more detailbelow. The encoded video data (404) (or encoded video bitstream (404)),depicted as a thin line to emphasize the lower data volume when comparedto the stream of video pictures (402), can be stored on a streamingserver (405) for future use. One or more streaming client subsystems,such as client subsystems (406) and (408) in FIG. 4 can access thestreaming server (405) to retrieve copies (407) and (409) of the encodedvideo data (404). A client subsystem (406) can include a video decoder(410), for example, in an electronic device (430). The video decoder(410) decodes the incoming copy (407) of the encoded video data andcreates an outgoing stream of video pictures (411) that can be renderedon a display (412) (e.g., display screen) or other rendering device (notdepicted). In some streaming systems, the encoded video data (404),(407), and (409) (e.g., video bitstreams) can be encoded according tocertain video coding/compression standards. Examples of those standardsinclude ITU-T Recommendation H.265. In an example, a video codingstandard under development is informally known as Versatile Video Coding(VVC). The disclosed subject matter may be used in the context of VVC.

It is noted that the electronic devices (420) and (430) can includeother components (not shown). For example, the electronic device (420)can include a video decoder (not shown) and the electronic device (430)can include a video encoder (not shown) as well.

FIG. 5 shows a block diagram of a video decoder (510) according to anembodiment of the present disclosure. The video decoder (510) can beincluded in an electronic device (530). The electronic device (530) caninclude a receiver (531) (e.g., receiving circuitry). The video decoder(510) can be used in the place of the video decoder (410) in the FIG. 4example.

The receiver (531) may receive one or more coded video sequences to bedecoded by the video decoder (510); in the same or another embodiment,one coded video sequence at a time, where the decoding of each codedvideo sequence is independent from other coded video sequences. Thecoded video sequence may be received from a channel (501), which may bea hardware/software link to a storage device which stores the encodedvideo data. The receiver (531) may receive the encoded video data withother data, for example, coded audio data and/or ancillary data streams,that may be forwarded to their respective using entities (not depicted).The receiver (531) may separate the coded video sequence from the otherdata. To combat network jitter, a buffer memory (515) may be coupled inbetween the receiver (531) and an entropy decoder/parser (520) (“parser(520)” henceforth). In certain applications, the buffer memory (515) ispart of the video decoder (510). In others, it can be outside of thevideo decoder (510) (not depicted). In still others, there can be abuffer memory (not depicted) outside of the video decoder (510), forexample to combat network jitter, and in addition another buffer memory(515) inside the video decoder (510), for example to handle playouttiming. When the receiver (531) is receiving data from a store/forwarddevice of sufficient bandwidth and controllability, or from anisosynchronous network, the buffer memory (515) may not be needed, orcan be small. For use on best effort packet networks such as theInternet, the buffer memory (515) may be required, can be comparativelylarge and can be advantageously of adaptive size, and may at leastpartially be implemented in an operating system or similar elements (notdepicted) outside of the video decoder (510).

The video decoder (510) may include the parser (520) to reconstructsymbols (521) from the coded video sequence. Categories of those symbolsinclude information used to manage operation of the video decoder (510),and potentially information to control a rendering device such as arender device (512) (e.g., a display screen) that is not an integralpart of the electronic device (530) but can be coupled to the electronicdevice (530), as was shown in FIG. 5 . The control information for therendering device(s) may be in the form of Supplemental EnhancementInformation (SEI messages) or Video Usability Information (VUI)parameter set fragments (not depicted). The parser (520) mayparse/entropy-decode the coded video sequence that is received. Thecoding of the coded video sequence can be in accordance with a videocoding technology or standard, and can follow various principles,including variable length coding, Huffman coding, arithmetic coding withor without context sensitivity, and so forth. The parser (520) mayextract from the coded video sequence, a set of subgroup parameters forat least one of the subgroups of pixels in the video decoder, based uponat least one parameter corresponding to the group. Subgroups can includeGroups of Pictures (GOPs), pictures, tiles, slices, macroblocks, CodingUnits (CUs), blocks, Transform Units (TUs), Prediction Units (PUs) andso forth. The parser (520) may also extract from the coded videosequence information such as transform coefficients, quantizer parametervalues, motion vectors, and so forth.

The parser (520) may perform an entropy decoding/parsing operation onthe video sequence received from the buffer memory (515), so as tocreate symbols (521).

Reconstruction of the symbols (521) can involve multiple different unitsdepending on the type of the coded video picture or parts thereof (suchas: inter and intra picture, inter and intra block), and other factors.Which units are involved, and how, can be controlled by the subgroupcontrol information that was parsed from the coded video sequence by theparser (520). The flow of such subgroup control information between theparser (520) and the multiple units below is not depicted for clarity.

Beyond the functional blocks already mentioned, the video decoder (510)can be conceptually subdivided into a number of functional units asdescribed below. In a practical implementation operating undercommercial constraints, many of these units interact closely with eachother and can, at least partly, be integrated into each other. However,for the purpose of describing the disclosed subject matter, theconceptual subdivision into the functional units below is appropriate.

A first unit is the scaler/inverse transform unit (551). Thescaler/inverse transform unit (551) receives a quantized transformcoefficient as well as control information, including which transform touse, block size, quantization factor, quantization scaling matrices,etc. as symbol(s) (521) from the parser (520). The scaler/inversetransform unit (551) can output blocks comprising sample values, thatcan be input into aggregator (555).

In some cases, the output samples of the scaler/inverse transform (551)can pertain to an intra coded block; that is: a block that is not usingpredictive information from previously reconstructed pictures, but canuse predictive information from previously reconstructed parts of thecurrent picture. Such predictive information can be provided by an intrapicture prediction unit (552). In some cases, the intra pictureprediction unit (552) generates a block of the same size and shape ofthe block under reconstruction, using surrounding already reconstructedinformation fetched from the current picture buffer (558). The currentpicture buffer (558) buffers, for example, partly reconstructed currentpicture and/or fully reconstructed current picture. The aggregator(555), in some cases, adds, on a per sample basis, the predictioninformation the intra prediction unit (552) has generated to the outputsample information as provided by the scaler/inverse transform unit(551).

In other cases, the output samples of the scaler/inverse transform unit(551) can pertain to an inter coded, and potentially motion compensatedblock. In such a case, a motion compensation prediction unit (553) canaccess reference picture memory (557) to fetch samples used forprediction. After motion compensating the fetched samples in accordancewith the symbols (521) pertaining to the block, these samples can beadded by the aggregator (555) to the output of the scaler/inversetransform unit (551) (in this case called the residual samples orresidual signal) so as to generate output sample information. Theaddresses within the reference picture memory (557) from where themotion compensation prediction unit (553) fetches prediction samples canbe controlled by motion vectors, available to the motion compensationprediction unit (553) in the form of symbols (521) that can have, forexample X, Y, and reference picture components. Motion compensation alsocan include interpolation of sample values as fetched from the referencepicture memory (557) when sub-sample exact motion vectors are in use,motion vector prediction mechanisms, and so forth.

The output samples of the aggregator (555) can be subject to variousloop filtering techniques in the loop filter unit (556). Videocompression technologies can include in-loop filter technologies thatare controlled by parameters included in the coded video sequence (alsoreferred to as coded video bitstream) and made available to the loopfilter unit (556) as symbols (521) from the parser (520), but can alsobe responsive to meta-information obtained during the decoding ofprevious (in decoding order) parts of the coded picture or coded videosequence, as well as responsive to previously reconstructed andloop-filtered sample values.

The output of the loop filter unit (556) can be a sample stream that canbe output to the render device (512) as well as stored in the referencepicture memory (557) for use in future inter-picture prediction.

Certain coded pictures, once fully reconstructed, can be used asreference pictures for future prediction. For example, once a codedpicture corresponding to a current picture is fully reconstructed andthe coded picture has been identified as a reference picture (by, forexample, the parser (520)), the current picture buffer (558) can becomea part of the reference picture memory (557), and a fresh currentpicture buffer can be reallocated before commencing the reconstructionof the following coded picture.

The video decoder (510) may perform decoding operations according to apredetermined video compression technology in a standard, such as ITU-TRec. H.265. The coded video sequence may conform to a syntax specifiedby the video compression technology or standard being used, in the sensethat the coded video sequence adheres to both the syntax of the videocompression technology or standard and the profiles as documented in thevideo compression technology or standard. Specifically, a profile canselect certain tools as the only tools available for use under thatprofile from all the tools available in the video compression technologyor standard. Also necessary for compliance can be that the complexity ofthe coded video sequence is within bounds as defined by the level of thevideo compression technology or standard. In some cases, levels restrictthe maximum picture size, maximum frame rate, maximum reconstructionsample rate (measured in, for example megasamples per second), maximumreference picture size, and so on. Limits set by levels can, in somecases, be further restricted through Hypothetical Reference Decoder(HRD) specifications and metadata for HRD buffer management signaled inthe coded video sequence.

In an embodiment, the receiver (531) may receive additional (redundant)data with the encoded video. The additional data may be included as partof the coded video sequence(s). The additional data may be used by thevideo decoder (510) to properly decode the data and/or to moreaccurately reconstruct the original video data. Additional data can bein the form of, for example, temporal, spatial, or signal noise ratio(SNR) enhancement layers, redundant slices, redundant pictures, forwarderror correction codes, and so on.

FIG. 6 shows a block diagram of a video encoder (603) according to anembodiment of the present disclosure. The video encoder (603) isincluded in an electronic device (620). The electronic device (620)includes a transmitter (640) (e.g., transmitting circuitry). The videoencoder (603) can be used in the place of the video encoder (403) in theFIG. 4 example.

The video encoder (603) may receive video samples from a video source(601) (that is not part of the electronic device (620) in the FIG. 6example) that may capture video image(s) to be coded by the videoencoder (603). In another example, the video source (601) is a part ofthe electronic device (620).

The video source (601) may provide the source video sequence to be codedby the video encoder (603) in the form of a digital video sample streamthat can be of any suitable bit depth (for example: 8 bit, 10 bit, 12bit, . . . ), any colorspace (for example, BT.601 Y CrCB, RGB, . . . ),and any suitable sampling structure (for example Y CrCb 4:2:0, Y CrCb4:4:4). In a media serving system, the video source (601) may be astorage device storing previously prepared video. In a videoconferencingsystem, the video source (601) may be a camera that captures local imageinformation as a video sequence. Video data may be provided as aplurality of individual pictures that impart motion when viewed insequence. The pictures themselves may be organized as a spatial array ofpixels, wherein each pixel can comprise one or more samples depending onthe sampling structure, color space, etc. in use. A person skilled inthe art can readily understand the relationship between pixels andsamples. The description below focuses on samples.

According to an embodiment, the video encoder (603) may code andcompress the pictures of the source video sequence into a coded videosequence (643) in real time or under any other time constraints asrequired by the application. Enforcing appropriate coding speed is onefunction of a controller (650). In some embodiments, the controller(650) controls other functional units as described below and isfunctionally coupled to the other functional units. The coupling is notdepicted for clarity. Parameters set by the controller (650) can includerate control related parameters (picture skip, quantizer, lambda valueof rate-distortion optimization techniques, . . . ), picture size, groupof pictures (GOP) layout, maximum motion vector search range, and soforth. The controller (650) can be configured to have other suitablefunctions that pertain to the video encoder (603) optimized for acertain system design.

In some embodiments, the video encoder (603) is configured to operate ina coding loop. As an oversimplified description, in an example, thecoding loop can include a source coder (630) (e.g., responsible forcreating symbols, such as a symbol stream, based on an input picture tobe coded, and a reference picture(s)), and a (local) decoder (633)embedded in the video encoder (603). The decoder (633) reconstructs thesymbols to create the sample data in a similar manner as a (remote)decoder also would create (as any compression between symbols and codedvideo bitstream is lossless in the video compression technologiesconsidered in the disclosed subject matter). The reconstructed samplestream (sample data) is input to the reference picture memory (634). Asthe decoding of a symbol stream leads to bit-exact results independentof decoder location (local or remote), the content in the referencepicture memory (634) is also bit exact between the local encoder andremote encoder. In other words, the prediction part of an encoder “sees”as reference picture samples exactly the same sample values as a decoderwould “see” when using prediction during decoding. This fundamentalprinciple of reference picture synchronicity (and resulting drift, ifsynchronicity cannot be maintained, for example because of channelerrors) is used in some related arts as well.

The operation of the “local” decoder (633) can be the same as of a“remote” decoder, such as the video decoder (510), which has alreadybeen described in detail above in conjunction with FIG. 5 . Brieflyreferring also to FIG. 5 , however, as symbols are available andencoding/decoding of symbols to a coded video sequence by an entropycoder (645) and the parser (520) can be lossless, the entropy decodingparts of the video decoder (510), including the buffer memory (515), andparser (520) may not be fully implemented in the local decoder (633).

An observation that can be made at this point is that any decodertechnology except the parsing/entropy decoding that is present in adecoder also necessarily needs to be present, in substantially identicalfunctional form, in a corresponding encoder. For this reason, thedisclosed subject matter focuses on decoder operation. The descriptionof encoder technologies can be abbreviated as they are the inverse ofthe comprehensively described decoder technologies. Only in certainareas a more detail description is required and provided below.

During operation, in some examples, the source coder (630) may performmotion compensated predictive coding, which codes an input picturepredictively with reference to one or more previously coded picture fromthe video sequence that were designated as “reference pictures.” In thismanner, the coding engine (632) codes differences between pixel blocksof an input picture and pixel blocks of reference picture(s) that may beselected as prediction reference(s) to the input picture.

The local video decoder (633) may decode coded video data of picturesthat may be designated as reference pictures, based on symbols createdby the source coder (630). Operations of the coding engine (632) mayadvantageously be lossy processes. When the coded video data may bedecoded at a video decoder (not shown in FIG. 6 ), the reconstructedvideo sequence typically may be a replica of the source video sequencewith some errors. The local video decoder (633) replicates decodingprocesses that may be performed by the video decoder on referencepictures and may cause reconstructed reference pictures to be stored inthe reference picture cache (634). In this manner, the video encoder(603) may store copies of reconstructed reference pictures locally thathave common content as the reconstructed reference pictures that will beobtained by a far-end video decoder (absent transmission errors).

The predictor (635) may perform prediction searches for the codingengine (632). That is, for a new picture to be coded, the predictor(635) may search the reference picture memory (634) for sample data (ascandidate reference pixel blocks) or certain metadata such as referencepicture motion vectors, block shapes, and so on, that may serve as anappropriate prediction reference for the new pictures. The predictor(635) may operate on a sample block-by-pixel block basis to findappropriate prediction references. In some cases, as determined bysearch results obtained by the predictor (635), an input picture mayhave prediction references drawn from multiple reference pictures storedin the reference picture memory (634).

The controller (650) may manage coding operations of the source coder(630), including, for example, setting of parameters and subgroupparameters used for encoding the video data.

Output of all aforementioned functional units may be subjected toentropy coding in the entropy coder (645). The entropy coder (645)translates the symbols as generated by the various functional units intoa coded video sequence, by lossless compressing the symbols according totechnologies such as Huffman coding, variable length coding, arithmeticcoding, and so forth.

The transmitter (640) may buffer the coded video sequence(s) as createdby the entropy coder (645) to prepare for transmission via acommunication channel (660), which may be a hardware/software link to astorage device which would store the encoded video data. The transmitter(640) may merge coded video data from the video coder (603) with otherdata to be transmitted, for example, coded audio data and/or ancillarydata streams (sources not shown).

The controller (650) may manage operation of the video encoder (603).During coding, the controller (650) may assign to each coded picture acertain coded picture type, which may affect the coding techniques thatmay be applied to the respective picture. For example, pictures oftenmay be assigned as one of the following picture types:

An Intra Picture (I picture) may be one that may be coded and decodedwithout using any other picture in the sequence as a source ofprediction. Some video codecs allow for different types of intrapictures, including, for example Independent Decoder Refresh (“IDR”)Pictures. A person skilled in the art is aware of those variants of Ipictures and their respective applications and features.

A predictive picture (P picture) may be one that may be coded anddecoded using intra prediction or inter prediction using at most onemotion vector and reference index to predict the sample values of eachblock.

A bi-directionally predictive picture (B Picture) may be one that may becoded and decoded using intra prediction or inter prediction using atmost two motion vectors and reference indices to predict the samplevalues of each block. Similarly, multiple-predictive pictures can usemore than two reference pictures and associated metadata for thereconstruction of a single block.

Source pictures commonly may be subdivided spatially into a plurality ofsample blocks (for example, blocks of 4×4, 8×8, 4×8, or 16×16 sampleseach) and coded on a block-by-block basis. Blocks may be codedpredictively with reference to other (already coded) blocks asdetermined by the coding assignment applied to the blocks' respectivepictures. For example, blocks of I pictures may be codednon-predictively or they may be coded predictively with reference toalready coded blocks of the same picture (spatial prediction or intraprediction). Pixel blocks of P pictures may be coded predictively, viaspatial prediction or via temporal prediction with reference to onepreviously coded reference picture. Blocks of B pictures may be codedpredictively, via spatial prediction or via temporal prediction withreference to one or two previously coded reference pictures.

The video encoder (603) may perform coding operations according to apredetermined video coding technology or standard, such as ITU-T Rec.H.265. In its operation, the video encoder (603) may perform variouscompression operations, including predictive coding operations thatexploit temporal and spatial redundancies in the input video sequence.The coded video data, therefore, may conform to a syntax specified bythe video coding technology or standard being used.

In an embodiment, the transmitter (640) may transmit additional datawith the encoded video. The source coder (630) may include such data aspart of the coded video sequence. Additional data may comprisetemporal/spatial/SNR enhancement layers, other forms of redundant datasuch as redundant pictures and slices, SEI messages, VUI parameter setfragments, and so on.

A video may be captured as a plurality of source pictures (videopictures) in a temporal sequence. Intra-picture prediction (oftenabbreviated to intra prediction) makes use of spatial correlation in agiven picture, and inter-picture prediction makes uses of the (temporalor other) correlation between the pictures. In an example, a specificpicture under encoding/decoding, which is referred to as a currentpicture, is partitioned into blocks. When a block in the current pictureis similar to a reference block in a previously coded and still bufferedreference picture in the video, the block in the current picture can becoded by a vector that is referred to as a motion vector. The motionvector points to the reference block in the reference picture, and canhave a third dimension identifying the reference picture, in casemultiple reference pictures are in use.

In some embodiments, a bi-prediction technique can be used in theinter-picture prediction. According to the bi-prediction technique, tworeference pictures, such as a first reference picture and a secondreference picture that are both prior in decoding order to the currentpicture in the video (but may be in the past and future, respectively,in display order) are used. A block in the current picture can be codedby a first motion vector that points to a first reference block in thefirst reference picture, and a second motion vector that points to asecond reference block in the second reference picture. The block can bepredicted by a combination of the first reference block and the secondreference block.

Further, a merge mode technique can be used in the inter-pictureprediction to improve coding efficiency.

According to some embodiments of the disclosure, predictions, such asinter-picture predictions and intra-picture predictions are performed inthe unit of blocks. For example, according to the HEVC standard, apicture in a sequence of video pictures is partitioned into coding treeunits (CTU) for compression, the CTUs in a picture have the same size,such as 64×64 pixels, 32×32 pixels, or 16×16 pixels. In general, a CTUincludes three coding tree blocks (CTBs), which are one luma CTB and twochroma CTBs. Each CTU can be recursively quadtree split into one ormultiple coding units (CUs). For example, a CTU of 64×64 pixels can besplit into one CU of 64×64 pixels, or 4 CUs of 32×32 pixels, or 16 CUsof 16×16 pixels. In an example, each CU is analyzed to determine aprediction type for the CU, such as an inter prediction type or an intraprediction type. The CU is split into one or more prediction units (PUs)depending on the temporal and/or spatial predictability. Generally, eachPU includes a luma prediction block (PB), and two chroma PBs. In anembodiment, a prediction operation in coding (encoding/decoding) isperformed in the unit of a prediction block. Using a luma predictionblock as an example of a prediction block, the prediction block includesa matrix of values (e.g., luma values) for pixels, such as 8×8 pixels,16×16 pixels, 8×16 pixels, 16×8 pixels, and the like.

FIG. 7 shows a diagram of a video encoder (703) according to anotherembodiment of the disclosure. The video encoder (703) is configured toreceive a processing block (e.g., a prediction block) of sample valueswithin a current video picture in a sequence of video pictures, andencode the processing block into a coded picture that is part of a codedvideo sequence. In an example, the video encoder (703) is used in theplace of the video encoder (403) in the FIG. 4 example.

In an HEVC example, the video encoder (703) receives a matrix of samplevalues for a processing block, such as a prediction block of 8×8samples, and the like. The video encoder (703) determines whether theprocessing block is best coded using intra mode, inter mode, orbi-prediction mode using, for example, rate-distortion optimization.When the processing block is to be coded in intra mode, the videoencoder (703) may use an intra prediction technique to encode theprocessing block into the coded picture; and when the processing blockis to be coded in inter mode or bi-prediction mode, the video encoder(703) may use an inter prediction or bi-prediction technique,respectively, to encode the processing block into the coded picture. Incertain video coding technologies, merge mode can be an inter pictureprediction submode where the motion vector is derived from one or moremotion vector predictors without the benefit of a coded motion vectorcomponent outside the predictors. In certain other video codingtechnologies, a motion vector component applicable to the subject blockmay be present. In an example, the video encoder (703) includes othercomponents, such as a mode decision module (not shown) to determine themode of the processing blocks.

In the FIG. 7 example, the video encoder (703) includes the interencoder (730), an intra encoder (722), a residue calculator (723), aswitch (726), a residue encoder (724), a general controller (721), andan entropy encoder (725) coupled together as shown in FIG. 7 .

The inter encoder (730) is configured to receive the samples of thecurrent block (e.g., a processing block), compare the block to one ormore reference blocks in reference pictures (e.g., blocks in previouspictures and later pictures), generate inter prediction information(e.g., description of redundant information according to inter encodingtechnique, motion vectors, merge mode information), and calculate interprediction results (e.g., predicted block) based on the inter predictioninformation using any suitable technique. In some examples, thereference pictures are decoded reference pictures that are decoded basedon the encoded video information.

The intra encoder (722) is configured to receive the samples of thecurrent block (e.g., a processing block), in some cases compare theblock to blocks already coded in the same picture, generate quantizedcoefficients after transform, and in some cases also intra predictioninformation (e.g., an intra prediction direction information accordingto one or more intra encoding techniques). In an example, the intraencoder (722) also calculates intra prediction results (e.g., predictedblock) based on the intra prediction information and reference blocks inthe same picture.

The general controller (721) is configured to determine general controldata and control other components of the video encoder (703) based onthe general control data. In an example, the general controller (721)determines the mode of the block, and provides a control signal to theswitch (726) based on the mode. For example, when the mode is the intramode, the general controller (721) controls the switch (726) to selectthe intra mode result for use by the residue calculator (723), andcontrols the entropy encoder (725) to select the intra predictioninformation and include the intra prediction information in thebitstream; and when the mode is the inter mode, the general controller(721) controls the switch (726) to select the inter prediction resultfor use by the residue calculator (723), and controls the entropyencoder (725) to select the inter prediction information and include theinter prediction information in the bitstream.

The residue calculator (723) is configured to calculate a difference(residue data) between the received block and prediction resultsselected from the intra encoder (722) or the inter encoder (730). Theresidue encoder (724) is configured to operate based on the residue datato encode the residue data to generate the transform coefficients. In anexample, the residue encoder (724) is configured to convert the residuedata from a spatial domain to a frequency domain, and generate thetransform coefficients. The transform coefficients are then subject toquantization processing to obtain quantized transform coefficients. Invarious embodiments, the video encoder (703) also includes a residuedecoder (728). The residue decoder (728) is configured to performinverse-transform, and generate the decoded residue data. The decodedresidue data can be suitably used by the intra encoder (722) and theinter encoder (730). For example, the inter encoder (730) can generatedecoded blocks based on the decoded residue data and inter predictioninformation, and the intra encoder (722) can generate decoded blocksbased on the decoded residue data and the intra prediction information.The decoded blocks are suitably processed to generate decoded picturesand the decoded pictures can be buffered in a memory circuit (not shown)and used as reference pictures in some examples.

The entropy encoder (725) is configured to format the bitstream toinclude the encoded block. The entropy encoder (725) is configured toinclude various information according to a suitable standard, such asthe HEVC standard. In an example, the entropy encoder (725) isconfigured to include the general control data, the selected predictioninformation (e.g., intra prediction information or inter predictioninformation), the residue information, and other suitable information inthe bitstream. Note that, according to the disclosed subject matter,when coding a block in the merge submode of either inter mode orbi-prediction mode, there is no residue information.

FIG. 8 shows a diagram of a video decoder (810) according to anotherembodiment of the disclosure. The video decoder (810) is configured toreceive coded pictures that are part of a coded video sequence, anddecode the coded pictures to generate reconstructed pictures. In anexample, the video decoder (810) is used in the place of the videodecoder (410) in the FIG. 4 example.

In the FIG. 8 example, the video decoder (810) includes an entropydecoder (871), an inter decoder (880), a residue decoder (873), areconstruction module (874), and an intra decoder (872) coupled togetheras shown in FIG. 8 .

The entropy decoder (871) can be configured to reconstruct, from thecoded picture, certain symbols that represent the syntax elements ofwhich the coded picture is made up. Such symbols can include, forexample, the mode in which a block is coded (such as, for example, intramode, inter mode, bi-predicted mode, the latter two in merge submode oranother submode), prediction information (such as, for example, intraprediction information or inter prediction information) that canidentify certain sample or metadata that is used for prediction by theintra decoder (872) or the inter decoder (880), respectively, residualinformation in the form of, for example, quantized transformcoefficients, and the like. In an example, when the prediction mode isinter or bi-predicted mode, the inter prediction information is providedto the inter decoder (880); and when the prediction type is the intraprediction type, the intra prediction information is provided to theintra decoder (872). The residual information can be subject to inversequantization and is provided to the residue decoder (873).

The inter decoder (880) is configured to receive the inter predictioninformation, and generate inter prediction results based on the interprediction information.

The intra decoder (872) is configured to receive the intra predictioninformation, and generate prediction results based on the intraprediction information.

The residue decoder (873) is configured to perform inverse quantizationto extract de-quantized transform coefficients, and process thede-quantized transform coefficients to convert the residual from thefrequency domain to the spatial domain. The residue decoder (873) mayalso require certain control information (to include the QuantizerParameter (QP)), and that information may be provided by the entropydecoder (871) (data path not depicted as this may be low volume controlinformation only).

The reconstruction module (874) is configured to combine, in the spatialdomain, the residual as output by the residue decoder (873) and theprediction results (as output by the inter or intra prediction modulesas the case may be) to form a reconstructed block, that may be part ofthe reconstructed picture, which in turn may be part of thereconstructed video. It is noted that other suitable operations, such asa deblocking operation and the like, can be performed to improve thevisual quality.

It is noted that the video encoders (403), (603), and (703), and thevideo decoders (410), (510), and (810) can be implemented using anysuitable technique. In an embodiment, the video encoders (403), (603),and (703), and the video decoders (410), (510), and (810) can beimplemented using one or more integrated circuits. In anotherembodiment, the video encoders (403), (603), and (603), and the videodecoders (410), (510), and (810) can be implemented using one or moreprocessors that execute software instructions.

The disclosure includes improvements on geometric partition mode withintra and inter predictions. In some embodiments, the intra mode orintra prediction is not valid for some specified geometric partitionswhen inter and intra prediction are allowed for GPM.

ITU-T VCEG (Q6/16) and ISO/IEC MPEG (JTC 1/SC 29/WG 11) published theH.265/HEVC (High Efficiency Video Coding) standard in 2013 (version 1),2014 (version 2), 2015 (version 3), and 2016 (version 4). In 2015, thetwo standard organizations jointly formed the JVET (Joint VideoExploration Team) to explore the potential of developing the next videocoding standard beyond HEVC. In October 2017, the two standardorganizations issued the Joint Call for Proposals on Video Compressionwith Capability beyond HEVC (CfP). By Feb. 15, 2018, total 22 CfPresponses on standard dynamic range (SDR), 12 CfP responses on highdynamic range (HDR), and 12 CfP responses on 360 video categories weresubmitted, respectively. In April 2018, all received CfP responses wereevaluated in the 122 MPEG/10th JVET meeting. As a result of thismeeting, JVET formally launched the standardization process ofnext-generation video coding beyond HEVC, the new standard was namedVersatile Video Coding (VVC), and JVET was renamed as Joint VideoExperts Team. In 2020, ITU-T VCEG (Q6/16) and ISO/IEC MPEG (JTC 1/SC29/WG 11) published the VVC video coding standard (version 1).

For each inter-predicted coding unit (CU), motion parameters arerequired for new coding features of VVC to be used for theinter-predicted sample generation. The motion parameters can includemotion vectors, reference picture indices, a reference picture listusage index, and additional information. The motion parameters can besignaled in an explicit or implicit manner. When a CU is coded with askip mode, the CU can be associated with one PU, and a significantresidual coefficient, a coded motion vector delta, or a referencepicture index may not be required. When a CU is coded with a merge mode,the motion parameters for the CU can be obtained from neighboring CUs.The neighboring CUs can include spatial and temporal candidates, andadditional schedules such as introduced in VVC. The merge mode can beapplied to any inter-predicted CU, not only for skip mode. Analternative to the merge mode is an explicit transmission of motionparameters, where a motion vector, a corresponding reference pictureindex for each reference picture list, a reference picture list usageflag, and other needed information can be signaled explicitly per CU.

In VVC, a VVC Test model (VTM) reference software can include a numberof new and refined inter prediction coding tools, which can be listed asfollows:

(1) Extended merge prediction

(2) Merge motion vector difference (MMVD)

(3) AMVP mode with symmetric MVD signalling

(4) Affine motion compensated prediction

(5) Subblock-based temporal motion vector prediction (SbTMVP)

(6) Adaptive motion vector resolution (AMVR)

(7) Motion field storage: 1/16^(th) luma sample MV storage and 8×8motion field compression

(8) Bi-prediction with CU-level weights (BCW)

(9) Bi-directional optical flow (BDOF)

(10) Decoder side motion vector refinement (DMVR)

(11) Combined inter and intra prediction (CIIP)

(12) Geometric partitioning mode (GPM)

In VTM 4, the merge candidate list can be constructed by including fivetypes of candidates in an order as follows:

1) Spatial MVP from spatial neighbour CUs,

2) Temporal MVP from collocated CUs,

3) History-based MVP from an FIFO table,

4) Pairwise average MVP, and

5) Zero MVs.

A size of a merge list can be signalled in a slice header and a maximumallowed size of the merge list can be 6 in VTM 4. For each CU coded inthe merge mode, an index of a best merge candidate can be encoded usinga truncated unary binarization (TU). A first bin of the merge index canbe coded with a context and a bypass coding can be used for other bins.

In a spatial candidate derivation, the derivation of spatial mergecandidates in VVC can be the same as the derivation of spatial mergecandidates in HEVC. A maximum of four merge candidates can be selectedamong candidates located in positions illustrated in FIG. 9 . As shownin FIG. 9 , a current block (901) can include neighboring blocks(902)-(906) located at positions A₀, A₁, B₀, B₁, and B₂ respectively. Anorder of derivation of spatial merge candidates can be B₁, A₁, B₀, A₀,and B₂. The position B₂ may be considered only when any CU (or block) atthe position A₀, B₀, B₁, or A₁ is not available (e.g., because the CUbelongs to another slice or tile) or is intra coded. After the candidate(or block) at position A₁ is added, the addition of the remainingcandidates (or blocks) can be subject to a redundancy check. Theredundancy check can ensure that candidates with the same motioninformation are excluded from the merge list so that coding efficiencyis improved. To reduce a computational complexity, not all possiblecandidate pairs are considered in the redundancy check. Instead, onlycandidate pairs linked with an arrow in FIG. 10 may be considered. Forexample, the redundancy check can be applied to 5 candidate pairs, suchas a candidate pair of A1 and B1 and a candidate pair of A1 and A0. Acandidate may be added to the merge list only if a correspondingcandidate that is used for redundancy check doesn't include the samemotion information. For example, the candidate B0 may be added to themerge list only if the corresponding candidate B1 does not include thesame motion information.

In a temporal candidate derivation, only one candidate maybe added to amerge list. For example, as shown in FIG. 11 , in the derivation of thetemporal merge candidate for a current CU (1114), a scaled motion vectorcan be derived based on a co-located CU (1104) which belongs to acollocated reference picture (1112). A reference picture list that isused for the derivation of the co-located CU (1104) can be explicitlysignaled in a slice header. The scaled motion vector for the temporalmerge candidate can be obtained as illustrated by a dotted line (1102)in FIG. 11 , which is scaled from a motion vector of the co-located CU(1104) using picture order count (POC) distances tb and td. tb can bedefined as a POC difference between a reference picture of a currentpicture (e.g., Curr_ref) (1106) and the current picture (e.g., Curr_pic)(1108). td can be defined as a POC difference between the referencepicture of the co-located picture (e.g., Col_ref) (1110) and theco-located picture (e.g., Col_pic) (1112). A reference picture index oftemporal merge candidate can be set equal to zero.

The position for the temporal candidate can be selected betweencandidates C₀ and C₁, as shown in FIG. 12 . If a CU at the position C₀is not available, is intra coded, or is outside of the current row ofCTUs, the position C₁ can be used. Otherwise, the position C₀ can beused in the derivation of the temporal merge candidate.

A geometric partition mode (GPM) can be applied to an inter prediction.The GPM may only be applied to CUs that have a size of 8×8 or a sizelarger than 8×8. The GPM can be signalled, for example using a CU-levelflag and act as one kind of merge mode. Other merge modes can includethe regular merge mode, the MMVD mode, the CIIP mode, and/or thesubblock merge mode.

When the GPM is used, a CU can be split into two geometric-shapedpartitions by using one of a plurality of partition manners. In anembodiment, 64 different partitioning manners can be applied in the GPM.The 64 different partitioning manners can be differentiated by 24 anglesthat are non-uniform quantized between 0 and 360° and up to 4 edgesrelative to a center of a CU. FIG. 13 shows exemplary 24 angles appliedin the GPM. FIG. 14 shows exemplary four possible partition edgesassociated with an angle with an index 3 in a CU (1402), where each ofthe partition edges can be associated with a respective distance index.The distance index can indicate a distance relative to a center of theCU (1402). In GPM, each geometric partition in the CU can beinter-predicted using a respective motion vector. In addition, onlyuni-prediction may be allowed for each partition. For example, eachpartition can have one motion vector and one reference index. Theconstraint that only the uni-prediction motion is allowed for eachpartition can ensure that only two motion compensated predictions areneeded for each CU, which is also applied in a conventionalbi-prediction.

If GPM is used for the current CU, a signal indicating the geometricpartition index, and two merge indices (one for each partition) canfurther be signalled. A maximum GPM candidate size can be signalled, forexample explicitly at a slice level. The number of maximum GPM candidatesize can specify a syntax binarization for GPM merge indices. After eachof the two geometric partitions is predicted, sample values along ageometric partition edge can be adjusted using a blending process withadaptive weights. A prediction signal for the whole CU can accordinglybe generated after the blending process. A transform and quantizationprocess can further be applied to the whole CU in other predictionmodes. Finally, the motion field of the CU that is predicted using theGPM can be stored.

In order to further improve compression efficiency, such as in the VVCstandard, template matching (TM) which refines the motion at the decoderside can be utilized. In the TM mode, motion is refined by constructinga template from left and above neighboring reconstructed samples and aclosest match can be determined between the template in the currentpicture and the reference frame.

TM can be applied to GPM. When a CU is coded in GPM, whether TM isapplied to refine each motion for the geometric partition can bedetermined. When the TM is chosen, a template can be constructed usingleft and above neighboring samples, and the motion can further berefined by finding a best match between the current template and areference area with a same template pattern in the reference frame. Therefined motion can be used to perform motion compensation for thegeometric partition and can further be stored in the motion field.

The GPM can be applied to support inter and intra prediction to enhancethe coding performance beyond VVC. For example, pre-defined intraprediction modes against (or regarding) a geometric partition line canbe selected in addition to motion vectors from a merge candidate listfor each geometric partition in a GPM-applied CU. An intra predictionmode or an inter prediction mode can be determined for each geometricpartition based on a flag. When the inter prediction is chosen, auni-prediction signal can be generated by MVs from the merge candidatelist. Otherwise, if the intra prediction mode is chosen, auni-prediction signal can be generated from the neighboring sampleswhich are predicted from a specified index of intra prediction mode. Thevariation of the possible intra prediction modes can be restricted bythe geometric shapes. Finally, the two uni-prediction signals can beblended in a same way as the ordinary GPM.

In order to reduce the complexity and the signalling overhead, thevariation of possible intra prediction modes can be studied (ordefined). For example, the effect of the variation of possible intraprediction modes on GPM with inter and intra prediction were studied fortwo exemplary configurations. The first configuration only triedparallel and perpendicular intra directional modes against (orregarding) the geometric partition line. In additional to the paralleland perpendicular intra angular modes against (or regarding) thegeometric partition line, a Planar mode was also tested in the secondconfiguration. Two or three possible intra prediction modes were testedfor the geometric partition in GPM with inter and intra prediction.Table 1 shows a pseudo code of GPM intra and inter prediction signaling.

TABLE 1 Pseudo code of GPM intra and inter prediction signaling   ... Ifgpm_flag is 1  ...  Parse intra/inter mode information ofpartition_index0  Parse intra/inter mode information of partition_index1 if one partition is intra and the other partition is inter   Parsemerge_gpm_partition_idx   Parse intra mode index for partition withintra prediction   Parse merge index for partition with inter prediction

As shown in Table 1, when a GPM flag (e.g., gpm flag) is 1 (or true), itindicates that the GPM is applied to a current block. Accordingly, thecurrent block can be partitioned into a first part (or first partition)and a second part (or second partition). A first partition index (e.g.,partition index0) can be parsed (or coded) to determine whether thefirst partition is inter coded or intra coded. A second partition index(e.g., partition index1) can be parsed (or coded) to determine whetherthe second partition is inter coded or intra coded. In response to oneof the first partition and the second partition being intra coded, andanother one of the first partition and the second partition being intercoded, a merge gpm partition index (e.g., merge_gpm_partition_idx) canbe decoded. The merge gpm partition index can indicate a partitioningmanner from a plurality of partition manners, such as 64 differentpartition manners shown in FIGS. 13-14 . Further, an intra mode indexcan be parsed (or coded) to indicate an intra mode from an intra modelist for the one of the first partition and the second partition that isintra coded. A merge index can be parsed to indicate a merge candidatefrom a merge candidate list for the other one of the first partition andthe second partition that is inter coded.

When an intra prediction mode is chosen for GPM, a flag can be signalledto indicate whether the intra prediction mode is used or not for twogeometric partitions. If the geometric partition is indicated togenerate a prediction from neighboring samples by using the intraprediction mode, only a certain amount of possible intra predictionmodes could be used. For example, up to three possible intra predictionmodes can be applied for GPM with inter and intra prediction. The threepossible intra prediction modes can include parallel, perpendicular, andplanar modes. In general, a limited number of intra prediction modes canresult in less coding efficiency. However, allowing all intra predictionmodes applicable to GPM can also lead to less coding efficiency becausesome modes are actually not available or inefficient.

In the disclosure, intra/inter mode information can be derived for eachpartition of the GPM using a merge gpm partition index (e.g.,merge_gpm_partition_idx). The merge gpm partition index can indicate apartitioning manner from a plurality of partition manners. In anexample, the plurality of partition manners can include 64 partitionmanners that are shown in FIG. 13-14 . FIGS. 15A, 15B, and 15C showthree exemplary partitions based on GPM. For example, as shown in FIG.15A, a rectangular block (1502) can be a CU that is partitioned into apartition A (1506) and a partition B (1508) by a straight line (1504)inside the CU (1502). The straight line (1504) can be a partition linewhich is geometrically inside the CU (1502) and indicated by the mergegpm partition index (e.g., merge_gpm_partition_idx).

In an embodiment, if both partitions of the CU cover a top left corner(0,0) of a CU (e.g., the partition line goes through, extends to, orintersects the top left corner), which of the partitions is coded withintra can be based on a width and a height of the block (or CU). In anexample, as shown in FIG. 15B, a width of a block (1510) is larger (orno smaller) than a height of the block (1510). Therefore, a partition A(1512) can be coded with an intra prediction and a partition B (1514)can be coded with an inter prediction. In an example, when the width ofthe block (1510) is smaller than the height of the block (1510), thepartition B (1514) can be coded with an intra prediction and thepartition A (1512) can be coded with an inter prediction. In anotherexample, when the width of the block (1510) is larger (or no smaller)than the height of the block (1510), the partition A (1512) can be codedwith an inter prediction and the partition B (1514) can be coded with anintra prediction. In yet another example, when the width of the block(1510) is smaller than the height of the block (1510), the partition B(1514) can be coded with inter and the partition A (1512) can be codedwith intra.

In an embodiment, if both partitions cover a top left corner (0,0) a CU,which of the partitions of the CU is coded with intra can be based on anumber of available top and left samples for the intra prediction. Forexample, as shown in FIG. 15B, the width of the block (1510) is larger(or no smaller) than the height of the block (1510). If top blocks (notshown) adjacent to the block (1510) are in another slice/tile which arenot available for the intra prediction for the current block (1510), andleft samples adjacent to the block (1510) are available for the intraprediction, the partition A (1512) can be coded in intra mode.

In another embodiment, when both top and left neighbors are notavailable for the intra prediction, GPM intra/inter may not be allowedfor a block that is partitioned by the GPM. For example, when both topand left neighbors are not available for the intra prediction, bothpartitions of the block by the GPM can be inter coded.

In the disclosure, a partition that contains more (or a larger portion)of a top left corner (0,0) pixel of a current CU can be coded with anintra prediction mode, and the other partition can be coded with aninter prediction mode.

In an embodiment, as shown in FIG. 15A, the partition A (1506) solelycontains the top left corner pixel of the CU (1502). Accordingly, thepartition A (1506) can be coded with the intra prediction and thepartition B (1508) can be coded with the inter prediction.

In an embodiment, the larger portion can correspond to an angle formedby the partition line and a side of the block or angles of thepartitions at the top left corner of the current CU. A larger angle canindicate that the partition includes a larger portion. As shown in FIG.15B, a partition line (1522) can divide the top left corner pixel, andan angle A in the partition A (1512) is larger than an angle B in thepartition B (1514). Accordingly, the partition A (1512) can contain more(or a larger portion) of the top left corner pixel. Thus, the partitionA (1512) can be coded with the intra prediction while the partition B(1514) can be coded with the inter prediction.

In another embodiment, when a first portion of the top corner pixelcontained in a first partition of the CU is equal to a second portion ofthe top corner pixel contained in the second partition of the CU,whether the first partition is intra coded or inter coded and whetherthe second partition is intra coded and inter coded can be based onneighboring reference samples of the CU that are available for intraprediction. For example, whether the first partition is intra coded orinter coded and whether the second partition is intra coded and intercoded can be based on which of top reference samples and left referencesamples are available for intra prediction and adjacent to one of thefirst partition and the second partition of the CU.

In an example shown in FIG. 15C, a partition line (1524) can divide atop left corner pixel of a CU (1516), and an angle A in a partition A(1518) can be equal to an angle B in a partition B (1520). Therefore,the partition A (1518) and the partition B (1520) can share the top leftcorner pixel of the CU (1516) equally. When the partition B (1520) isadjacent to top reference samples that are available for intraprediction, the partition B (1520) can be coded with the intraprediction and the partition A (1518) can be coded with the interprediction.

In another example shown in FIG. 15C, when the partition A (1518) isadjacent to left reference samples of the CU (1518) that are availablefor intra prediction, the partition A (1518) can be coded with the intraprediction while the partition B (1520) can be coded with the interprediction.

In the disclosure, a merge gpm partition index (e.g.,merge_gpm_partition_idx) can be signaled at first, and intra/inter modeinformation of a partition_index0 and a partition_index1 from the GPMcan be signaled subsequently. A pseudo code of GPM intra and interprediction signaling can be shown in Table 2, where the merge gpmpartition index can be signaled prior to signaling the intra/inter modeinformation of the partition_index0 and the partition_index1.

TABLE 2 Pseudo code of GPM intra and inter prediction signaling   ... Ifgpm_flag is 1  ...  Parse merge_gpm_partition_idx  Parse intra/intermode information of partition_index0  Parse intra/inter mode informationof partition_index1  if one partition is intra and the other partitionis inter   Parse intra mode index for partition with intra prediction  Parse merge index for partition with inter prediction

As shown in Table 2, when a GPM flag (e.g., gpm flag) is 1 (or true), itindicates that the GPM is applied to a current block. Accordingly, thecurrent block can be partitioned into a first part (or first partition)and a second part (or second partition). A merge gpm partition index(e.g., merge_gpm_partition_idx) can be decoded. The merge gpm partitionindex can indicate a partitioning manner from a plurality of partitionmanners. The plurality of partition manners can be shown in FIGS. 13-14. A first partition index (e.g., partition_index0) can be parsed (orcoded) to determine whether the first partition is inter coded or intracoded. A second partition index (e.g., partition_index 1) can be parsed(or coded) to determine whether the second partition is inter coded orintra coded. When one of the first partition and the second partition isintra coded, and another one of the first partition and the secondpartition is inter coded, an intra mode index can be parsed (or coded)to indicate an intra mode from an intra mode list for the one of thefirst partition and the second partition that is intra coded. A mergeindex can be parsed to indicate a merge candidate from a merge candidatelist for the other one of the first partition and the second partitionthat is inter coded.

In the disclosure, the first partition index (e.g., partition_index0)and the second partition index (e.g., partition_index1) may not besignaled to indicate whether the first partition is intra coded or intercoded and whether the second partition is intra coded or inter coded.When the merge gpm partition index (e.g., merge_gpm_partition_idx) isparsed, whether the first partition is intra coded or inter coded andwhether the second partition is intra coded or inter coded can bederived based a location of the partition line, which can be shown inFIGS. 15A-15C and discussions related thereto. For example, as shown inFIG. 15B, the first partition can be intra coded and the secondpartition can be inter coded when the straight partition line (1522)intersects a top left corner of the CU (1510), and a width of the CU(1510) is equal to or larger than a height of the CU (1510).

In an embodiment, an intra and inter flag (e.g.,one_intra_one_inter_flag) can be provided to replace the first partitionindex (e.g., partition_index0) and the second partition index (e.g.,partition_index1) which are provided in Table 2. The intra and interflag (e.g., one_intra_one_inter_flag) can indicate whether one of thefirst partition and the second partition is intra coded and another oneof the first partition and the second partition is inter coded. Forexample, when the intra and inter flag (e.g., one_intra_one_inter_flag)is 1 (or true), it can indicate that one partition is intra coded andthe other is inter coded. When the intra and inter flag (e.g.,one_intra_one_inter_flag) is 0 (or false), both partitions can be intercoded or inter coded. Table 3 shows a pseudo code of GPM intra and interprediction signaling, where the intra and inter flag is included.

TABLE 3 Pseudo code of GPM intra and inter prediction signaling   ... Ifgpm_flag is 1  ...  Parse merge_gpm_partition_idx  Parseone_intra_one_inter_flag  if one partition is intra and the otherpartition is inter   Parse intra mode index for partition with intraprediction   Parse merge index for partition with inter prediction

As shown in Table 3, when a GPM flag (e.g., gpm_flag) is 1 (or true), itindicates that the GPM is applied to a current block. Accordingly, thecurrent block can be partitioned into a first part (or first partition)and a second part (or second partition). A merge gpm partition index(e.g., merge_gpm_partition_idx) can subsequently be coded. The merge gpmpartition index can indicate a partitioning manner from a plurality ofpartition manners. The plurality of partition manners can be shown inFIGS. 13-14 . Further, an intra and inter flag (e.g.,one_intra_one_inter_flag) can be parsed (or coded) to determine whetherone of the first partition and the second partition is intra coded andanother one of the first partition and the second partition is intercoded. When the intra and inter flag indicates that one of the firstpartition and the second partition is intra coded and another one of thefirst partition and the second partition is inter coded, an intra modeindex can be parsed (or coded) to indicate an intra mode from a intramode list for the one of the first partition and the second partitionthat is intra coded. A merge index can be parsed to indicate a mergecandidate from a merge candidate list for the other one of the firstpartition and the second partition that is inter coded.

FIG. 16 shows a flow chart outlining an exemplary decoding process(1600) according to some embodiments of the disclosure. FIG. 17 shows aflow chart outlining an exemplary encoding process (1700) according tosome embodiments of the disclosure. The proposed processes may be usedseparately or combined in any order. Further, each of the processes (orembodiments), encoder, and decoder may be implemented by processingcircuitry (e.g., one or more processors or one or more integratedcircuits). In one example, the one or more processors execute a programthat is stored in a non-transitory computer-readable medium.

In embodiments, any operations of processes (e.g., (1600) and (1700))may be combined or arranged in any amount or order, as desired. Inembodiments, two or more of the operations of the processes (e.g.,(1600) and (1700)) may be performed in parallel.

The processes (e.g., (1600) and (1700)) can be used in thereconstruction and/or encoding of a block, so as to generate aprediction block for the block under reconstruction. In variousembodiments, the processes (e.g., (1600) and (1700)) are executed byprocessing circuitry, such as the processing circuitry in the terminaldevices (310), (320), (330) and (340), the processing circuitry thatperforms functions of the video encoder (403), the processing circuitrythat performs functions of the video decoder (410), the processingcircuitry that performs functions of the video decoder (510), theprocessing circuitry that performs functions of the video encoder (603),and the like. In some embodiments, the processes (e.g., (1600) and(1700)) are implemented in software instructions, thus when theprocessing circuitry executes the software instructions, the processingcircuitry performs the processes (e.g., (1600) and (1700)).

As shown in FIG. 16 , the process (1600) can start from (S1601) andproceed to (S1610). At (S1610), coded information of a coding unit (CU)in a current picture can be received from a coded video bitstream.

At (S1620), the CU can be partitioned into a first partition and asecond partition based on a partition index in the coded information.The partition index can indicate a geometric partition mode (GPM) inwhich the CU is partitioned into the first partition and the secondpartition by a straight partition line.

At (S1630), based on a location of the straight partition line in theCU, (i) whether a first prediction mode of the first partition of the CUis one of an intra mode and an inter mode and (ii) whether a secondprediction mode of the second partition of the CU is one of the intramode and the inter mode can be determined.

At (S1640), the first partition of the CU can be reconstructed based onthe determined first prediction mode and the second partition of the CUcan be reconstructed based on the determined second prediction mode

Then, the process proceeds to (S1699) and terminates.

In an example, in response to the straight partition line intersecting atop left corner of the CU, the first prediction mode of the firstpartition can be determined as the intra mode and the second predictionmode of the second partition can be determined as the inter mode basedon a width of the CU being equal to or larger than a height of the CU.

In another example, in response to the straight partition lineintersecting a top left corner of the CU, the first prediction mode ofthe first partition can be determined as the inter mode and the secondprediction mode of the second partition can be determined as the intramode based on a width of the CU being smaller than a height of the CU.

In yet another example, in response to the straight partition lineintersecting a top left corner of the CU, the first prediction mode ofthe first partition and the second prediction mode of the secondpartition can be determined based on which of a top reference sample anda left reference sample adjacent to the CU is available for intraprediction.

For example, based on (i) the left reference sample being adjacent tothe first partition of the CU and available for the intra prediction and(ii) the top reference sample being unavailable for the intraprediction, the first prediction mode of the first partition can bedetermined as the intra mode and the second prediction mode of thesecond partition can be determined as the inter mode.

In some embodiments, the first prediction mode of the first partitionand the second prediction mode of the second partition can be determinedbased on which one of the first partition and the second partition ofthe CU contains a larger portion of a top corner pixel of the CU.

In some embodiments, based on the first partition of the CU containingthe larger portion of the top corner pixel of the CU, the firstprediction mode of the first partition can be determined as the intramode and the second prediction mode of the second partition can bedetermined as the inter mode.

In some embodiments, in response to a first portion of the top cornerpixel contained in the first partition being equal to a second portionof the top corner pixel contained in the second partition, the firstprediction mode and the second prediction mode can be determined basedon which of a top reference sample and a left reference sample areadjacent to one of the first partition and the second partition.

In some embodiments, whether the first partition of the CU is intracoded or inter coded can be determined based on a first index. Whetherthe second partition of the CU is intra coded or inter coded can bedetermined based on a second index. In response to one of the firstpartition and the second partition being intra coded and another one ofthe first partition and the second partition being inter coded, theintra mode can be determined from an intra mode list for the one of thefirst partition and the second partition that is intra coded based on anintra mode index that is included in the coded information. A mergecandidate for the inter mode can be determined from a merge candidatelist for the other one of the first partition and the second partitionthat is inter coded based on a merge index that is included in the codedinformation.

In the process (1600), whether one of the first partition and the secondpartition of the CU is intra coded and another one of the firstpartition and the second partition of the CU is inter coded can bedetermined based on a flag included in the coded information. Inresponse to the one of the first partition and the second partition ofthe CU being intra coded and the other one of the first partition andthe second partition of the CU being inter coded, the intra mode can bedetermined from an intra mode list for the one of the first partitionand the second partition that is intra coded based on an intra modeindex included in the coded information. A merge candidate for the intermode can be determined from a merge candidate list for the other one ofthe first partition and the second partition that is inter coded basedon a merge index included in the coded information.

The process (1600) can be suitably adapted. Step(s) in the process(1600) can be modified and/or omitted. Additional step(s) can be added.Any suitable order of implementation can be used.

As shown in FIG. 17 , the process (1700) can start from (S1701) andproceed to (S1710). At (S1710), a coding unit (CU) of a picture can bepartitioned into a first partition and a second partition based on ageometric partition mode (GPM) in which the CU is partitioned into thefirst partition and the second partition by a straight partition line.

At (S1720), (i) whether a first prediction mode of the first partitionof the CU is one of an intra mode and an inter mode and (ii) whether asecond prediction mode of the second partition of the CU is one of theintra mode and the inter mode can be determined based on a location ofthe straight partition line in the CU.

At (S1730), prediction sample values for the first partition of the CUcan be determined based on the determined first prediction mode andprediction sample values for the second partition of the CU can bedetermined based on the determined second prediction mode.

At (S1740), coded information of the CU can be generated. The codinginformation can indicate that the first prediction mode of the firstpartition of the CU and the second prediction mode of the secondpartition of the CU are determined based on the location of the straightpartition line of the GPM in the CU.

Then, the process proceeds to (S1799) and terminates.

The process (1700) can be suitably adapted. Step(s) in the process(1700) can be modified and/or omitted. Additional step(s) can be added.Any suitable order of implementation can be used.

The techniques described above, can be implemented as computer softwareusing computer-readable instructions and physically stored in one ormore computer-readable media. For example, FIG. 18 shows a computersystem (1800) suitable for implementing certain embodiments of thedisclosed subject matter.

The computer software can be coded using any suitable machine code orcomputer language, that may be subject to assembly, compilation,linking, or like mechanisms to create code comprising instructions thatcan be executed directly, or through interpretation, micro-codeexecution, and the like, by one or more computer central processingunits (CPUs), Graphics Processing Units (GPUs), and the like.

The instructions can be executed on various types of computers orcomponents thereof, including, for example, personal computers, tabletcomputers, servers, smartphones, gaming devices, internet of thingsdevices, and the like.

The components shown in FIG. 18 for computer system (1800) are exemplaryin nature and are not intended to suggest any limitation as to the scopeof use or functionality of the computer software implementingembodiments of the present disclosure. Neither should the configurationof components be interpreted as having any dependency or requirementrelating to any one or combination of components illustrated in theexemplary embodiment of a computer system (1800).

Computer system (1800) may include certain human interface inputdevices. Such a human interface input device may be responsive to inputby one or more human users through, for example, tactile input (such as:keystrokes, swipes, data glove movements), audio input (such as: voice,clapping), visual input (such as: gestures), olfactory input (notdepicted). The human interface devices can also be used to capturecertain media not necessarily directly related to conscious input by ahuman, such as audio (such as: speech, music, ambient sound), images(such as: scanned images, photographic images obtain from a still imagecamera), video (such as two-dimensional video, three-dimensional videoincluding stereoscopic video).

Input human interface devices may include one or more of (only one ofeach depicted): keyboard (1801), mouse (1802), trackpad (1803), touchscreen (1810), data-glove (not shown), joystick (1805), microphone(1806), scanner (1807), camera (1808).

Computer system (1800) may also include certain human interface outputdevices. Such human interface output devices may be stimulating thesenses of one or more human users through, for example, tactile output,sound, light, and smell/taste. Such human interface output devices mayinclude tactile output devices (for example tactile feedback by thetouch-screen (1810), data-glove (not shown), or joystick (1805), butthere can also be tactile feedback devices that do not serve as inputdevices), audio output devices (such as: speakers (1809), headphones(not depicted)), visual output devices (such as screens (1810) toinclude CRT screens, LCD screens, plasma screens, OLED screens, eachwith or without touch-screen input capability, each with or withouttactile feedback capability—some of which may be capable to output twodimensional visual output or more than three dimensional output throughmeans such as stereographic output; virtual-reality glasses (notdepicted), holographic displays and smoke tanks (not depicted)), andprinters (not depicted).

Computer system (1800) can also include human accessible storage devicesand their associated media such as optical media including CD/DVD ROM/RW(1820) with CD/DVD or the like media (1821), thumb-drive (1822),removable hard drive or solid state drive (1823), legacy magnetic mediasuch as tape and floppy disc (not depicted), specialized ROM/ASIC/PLDbased devices such as security dongles (not depicted), and the like.

Those skilled in the art should also understand that term “computerreadable media” as used in connection with the presently disclosedsubject matter does not encompass transmission media, carrier waves, orother transitory signals.

Computer system (1800) can also include an interface (1854) to one ormore communication networks (1855). Networks can for example bewireless, wireline, optical. Networks can further be local, wide-area,metropolitan, vehicular and industrial, real-time, delay-tolerant, andso on. Examples of networks include local area networks such asEthernet, wireless LANs, cellular networks to include GSM, 3G, 4G, 5G,LTE and the like, TV wireline or wireless wide area digital networks toinclude cable TV, satellite TV, and terrestrial broadcast TV, vehicularand industrial to include CANBus, and so forth. Certain networkscommonly require external network interface adapters that attached tocertain general purpose data ports or peripheral buses (1849) (such as,for example USB ports of the computer system (1800)); others arecommonly integrated into the core of the computer system (1800) byattachment to a system bus as described below (for example Ethernetinterface into a PC computer system or cellular network interface into asmartphone computer system). Using any of these networks, computersystem (1800) can communicate with other entities. Such communicationcan be uni-directional, receive only (for example, broadcast TV),uni-directional send-only (for example CANbus to certain CANbusdevices), or bi-directional, for example to other computer systems usinglocal or wide area digital networks. Certain protocols and protocolstacks can be used on each of those networks and network interfaces asdescribed above.

Aforementioned human interface devices, human-accessible storagedevices, and network interfaces can be attached to a core (1840) of thecomputer system (1800).

The core (1840) can include one or more Central Processing Units (CPU)(1841), Graphics Processing Units (GPU) (1842), specialized programmableprocessing units in the form of Field Programmable Gate Areas (FPGA)(1843), hardware accelerators for certain tasks (1844), graphicsadapters (1850), and so forth. These devices, along with Read-onlymemory (ROM) (1845), Random-access memory (1846), internal mass storagesuch as internal non-user accessible hard drives, SSDs, and the like(1847), may be connected through a system bus (1848). In some computersystems, the system bus (1848) can be accessible in the form of one ormore physical plugs to enable extensions by additional CPUs, GPU, andthe like. The peripheral devices can be attached either directly to thecore's system bus (1848), or through a peripheral bus (1849). In anexample, the screen (1810) can be connected to the graphics adapter(1850). Architectures for a peripheral bus include PCI, USB, and thelike.

CPUs (1841), GPUs (1842), FPGAs (1843), and accelerators (1844) canexecute certain instructions that, in combination, can make up theaforementioned computer code. That computer code can be stored in ROM(1845) or RAM (1846). Transitional data can be also be stored in RAM(1846), whereas permanent data can be stored for example, in theinternal mass storage (1847). Fast storage and retrieve to any of thememory devices can be enabled through the use of cache memory, that canbe closely associated with one or more CPU (1841), GPU (1842), massstorage (1847), ROM (1845), RAM (1846), and the like.

The computer readable media can have computer code thereon forperforming various computer-implemented operations. The media andcomputer code can be those specially designed and constructed for thepurposes of the present disclosure, or they can be of the kind wellknown and available to those having skill in the computer software arts.

As an example and not by way of limitation, the computer system havingarchitecture (1800), and specifically the core (1840) can providefunctionality as a result of processor(s) (including CPUs, GPUs, FPGA,accelerators, and the like) executing software embodied in one or moretangible, computer-readable media. Such computer-readable media can bemedia associated with user-accessible mass storage as introduced above,as well as certain storage of the core (1840) that are of non-transitorynature, such as core-internal mass storage (1847) or ROM (1845). Thesoftware implementing various embodiments of the present disclosure canbe stored in such devices and executed by core (1840). Acomputer-readable medium can include one or more memory devices orchips, according to particular needs. The software can cause the core(1840) and specifically the processors therein (including CPU, GPU,FPGA, and the like) to execute particular processes or particular partsof particular processes described herein, including defining datastructures stored in RAM (1846) and modifying such data structuresaccording to the processes defined by the software. In addition or as analternative, the computer system can provide functionality as a resultof logic hardwired or otherwise embodied in a circuit (for example:accelerator (1844)), which can operate in place of or together withsoftware to execute particular processes or particular parts ofparticular processes described herein. Reference to software canencompass logic, and vice versa, where appropriate. Reference to acomputer-readable media can encompass a circuit (such as an integratedcircuit (IC)) storing software for execution, a circuit embodying logicfor execution, or both, where appropriate. The present disclosureencompasses any suitable combination of hardware and software.

Appendix A: Acronyms

JEM: joint exploration modelVVC: versatile video codingBMS: benchmark set

MV: Motion Vector HEVC: High Efficiency Video Coding SEI: SupplementaryEnhancement Information VUI: Video Usability Information GOPs: Groups ofPictures TUs: Transform Units, PUs: Prediction Units CTUs: Coding TreeUnits CTBs: Coding Tree Blocks PBs: Prediction Blocks HRD: HypotheticalReference Decoder SNR: Signal Noise Ratio CPUs: Central Processing UnitsGPUs: Graphics Processing Units CRT: Cathode Ray Tube LCD:Liquid-Crystal Display OLED: Organic Light-Emitting Diode CD: CompactDisc DVD: Digital Video Disc ROM: Read-Only Memory RAM: Random AccessMemory ASIC: Application-Specific Integrated Circuit PLD: ProgrammableLogic Device LAN: Local Area Network

GSM: Global System for Mobile communications

LTE: Long-Term Evolution CANBus: Controller Area Network Bus USB:Universal Serial Bus PCI: Peripheral Component Interconnect FPGA: FieldProgrammable Gate Areas

SSD: solid-state drive

IC: Integrated Circuit CU: Coding Unit

While this disclosure has described several exemplary embodiments, thereare alterations, permutations, and various substitute equivalents, whichfall within the scope of the disclosure. It will thus be appreciatedthat those skilled in the art will be able to devise numerous systemsand methods which, although not explicitly shown or described herein,embody the principles of the disclosure and are thus within the spiritand scope thereof.

What is claimed is:
 1. A method of video decoding performed in a videodecoder, the method comprising: receiving coded information of a codingunit (CU) in a current picture from a coded video bitstream;partitioning the CU into a first partition and a second partition basedon a partition index in the coded information, the partition indexindicating a geometric partition mode (GPM) in which the CU ispartitioned into the first partition and the second partition by astraight partition line; determining (i) whether a first prediction modeof the first partition of the CU is one of an intra mode and an intermode, and (ii) whether a second prediction mode of the second partitionof the CU is one of the intra mode and the inter mode, based on alocation of the straight partition line in the CU; and reconstructingthe first partition of the CU based on the determined first predictionmode and reconstructing the second partition of the CU based on thedetermined second prediction mode.
 2. The method of claim 1, wherein thedetermining further comprises: in response to the straight partitionline intersecting a top left corner of the CU, determining that thefirst prediction mode of the first partition is the intra mode and thesecond prediction mode of the second partition is the inter mode basedon a width of the CU being equal to or larger than a height of the CU.3. The method of claim 1, wherein the determining further comprises: inresponse to the straight partition line intersecting a top left cornerof the CU, determining that the first prediction mode of the firstpartition is the inter mode and the second prediction mode of the secondpartition is the intra mode based on a width of the CU being smallerthan a height of the CU.
 4. The method of claim 1, wherein thedetermining further comprises: in response to the straight partitionline intersecting a top left corner of the CU, determining the firstprediction mode of the first partition and the second prediction mode ofthe second partition based on which of a top reference sample and a leftreference sample adjacent to the CU is available for intra prediction.5. The method of claim 4, wherein the determining further comprises:based on (i) the left reference sample being adjacent to the firstpartition of the CU and available for the intra prediction and (ii) thetop reference sample being unavailable for the intra prediction,determining that the first prediction mode of the first partition is theintra mode and the second prediction mode of the second partition is theinter mode.
 6. The method of claim 1, wherein the determining furthercomprises: determining the first prediction mode of the first partitionand the second prediction mode of the second partition based on whichone of the first partition and the second partition of the CU contains alarger portion of a top corner pixel of the CU.
 7. The method of claim6, wherein the determining further comprises: based on the firstpartition of the CU containing the larger portion of the top cornerpixel of the CU, determining that the first prediction mode of the firstpartition is the intra mode and the second prediction mode of the secondpartition is the inter mode.
 8. The method of claim 6, wherein thedetermining further comprises: in response to a first portion of the topcorner pixel contained in the first partition being equal to a secondportion of the top corner pixel contained in the second partition,determining the first prediction mode and the second prediction modebased on which of a top reference sample and a left reference sample areadjacent to one of the first partition and the second partition.
 9. Themethod of claim 1, wherein the determining further comprises:determining whether the first partition of the CU is intra coded orinter coded based on a first index; determining whether the secondpartition of the CU is intra coded or inter coded based on a secondindex; and in response to one of the first partition and the secondpartition being intra coded and another one of the first partition andthe second partition being inter coded, determining the intra mode froman intra mode list for the one of the first partition and the secondpartition that is intra coded based on an intra mode index included inthe coded information; and determining a merge candidate for the intermode from a merge candidate list for the other one of the firstpartition and the second partition that is inter coded based on a mergeindex included in the coded information.
 10. The method of claim 1,wherein the determining further comprises: determining whether one ofthe first partition and the second partition of the CU is intra codedand another one of the first partition and the second partition of theCU is inter coded based on a flag included in the coded information; andin response to the one of the first partition and the second partitionof the CU being intra coded and the other one of the first partition andthe second partition of the CU being inter coded, determining the intramode from an intra mode list for the one of the first partition and thesecond partition that is intra coded based on an intra mode indexincluded in the coded information; and determining a merge candidate forthe inter mode from a merge candidate list for the other one of thefirst partition and the second partition that is inter coded based on amerge index included in the coded information.
 11. An apparatus,comprising: processing circuitry configured to: receive codedinformation of a coding unit (CU) in a current picture from a codedvideo bitstream; partition the CU into a first partition and a secondpartition based on a partition index in the coded information, thepartition index indicating a geometric partition mode (GPM) in which theCU is partitioned into the first partition and the second partition by astraight partition line; determine (i) whether a first prediction modeof the first partition of the CU is one of an intra mode and an intermode, and (ii) whether a second prediction mode of the second partitionof the CU is one of the intra mode and the inter mode based, on alocation of the straight partition line in the CU; and reconstruct thefirst partition of the CU based on the determined first prediction modeand reconstructing the second partition of the CU based on thedetermined second prediction mode.
 12. The apparatus of claim 11,wherein the processing circuitry is further configured to: in responseto the straight partition line intersecting a top left corner of the CU,determine that the first prediction mode of the first partition is theintra mode and the second prediction mode of the second partition is theinter mode based on a width of the CU being equal to or larger than aheight of the CU.
 13. The apparatus of claim 11, wherein the processingcircuitry is further configured to: in response to the straightpartition line intersecting a top left corner of the CU, determine thatthe first prediction mode of the first partition is the inter mode andthe second prediction mode of the second partition is the intra modebased on the width of the CU being smaller than the height of the CU.14. The apparatus of claim 11, wherein the processing circuitry isfurther configured to: in response to the straight partition lineintersecting a top left corner of the CU, determine the first predictionmode of the first partition and the second prediction mode of the secondpartition based on which of a top reference sample and a left referencesample adjacent to the CU is available for intra prediction.
 15. Theapparatus of claim 14, wherein the processing circuitry is furtherconfigured to: based on (i) the left reference sample being adjacent tothe first partition of the CU and available for the intra prediction and(ii) the top reference sample being unavailable for the intraprediction, determine that the first prediction mode of the firstpartition is the intra mode and the second prediction mode of the secondpartition is the inter mode.
 16. The apparatus of claim 11, wherein theprocessing circuitry is further configured to: determine the firstprediction mode of the first partition and the second prediction mode ofthe second partition based on which one of the first partition and thesecond partition of the CU contains a larger portion of a top cornerpixel of the CU.
 17. The apparatus of claim 16, wherein the processingcircuitry is further configured to: based on the first partition of theCU containing the larger portion of the top corner pixel of the CU,determine that the first prediction mode of the first partition is theintra mode and the second prediction mode of the second partition is theinter mode.
 18. The apparatus of claim 16, wherein the processingcircuitry is further configured to: in response to a first portion ofthe top corner pixel contained in the first partition being equal to asecond portion of the top corner pixel contained in the secondpartition, determine the first prediction mode and the second predictionmode based on which of a top reference sample and a left referencesample are adjacent to one of the first partition and the secondpartition.
 19. The apparatus of claim 11, wherein the processingcircuitry is further configured to: determine whether the firstpartition of the CU is intra coded or inter coded based on a firstindex; determine whether the second partition of the CU is intra codedor inter coded based on a second index; and in response to one of thefirst partition and the second partition being intra coded and anotherone of the first partition and the second partition being inter coded,determine the intra mode from an intra mode list for the one of thefirst partition and the second partition that is intra coded based on anintra mode index included in the coded information; and determine amerge candidate for the inter mode from a merge candidate list for theother one of the first partition and the second partition that is intercoded based on a merge index included in the coded information.
 20. Theapparatus of claim 11, wherein the processing circuitry is furtherconfigured to: determine whether one of the first partition and thesecond partition of the CU is intra coded and another one of the firstpartition and the second partition of the CU is inter coded based on aflag included in the coded information; and in response to the one ofthe first partition and the second partition of the CU being intra codedand the other one of the first partition and the second partition of theCU being inter coded, determine the intra mode from an intra mode listfor the one of the first partition and the second partition that isintra coded based on an intra mode index included in the codedinformation; and determine a merge candidate for the inter mode from amerge candidate list for the other one of the first partition and thesecond partition that is inter coded based on a merge index included inthe coded information.